Since Canada Montreal Protocol (1987) presented a specific objective to replace halon fire extinguishing agent, countries around the world are committed to the research of new fire extinguishing technology. The direction of people's efforts is to acquire a fire extinguishing technology that has a high fire extinguishing efficiency and is free of contamination to the environment.
As being environment friendly, gas extinguishing systems, dry powder extinguishing systems and water-based extinguishing systems have been widely used as alternatives for halon fire extinguishing agent. Extinguishing systems of inert gases such as carbon dioxide, IG541, etc. physically extinguish fire due to suffocation by lowering the oxygen concentration of firing area. This fire extinguishing mode easily poses a threat to the personal safety. The dry powder tire extinguishing system ejects powder under a pressurized gas so that the powder contacts with the flame and extinguishes the flame due to physical and chemical inhibition action. Water spraying fire extinguishing system plays a triple role, cooling, suffocation and isolating thermal radiation by water mist, to control fires, suppress fires and extinguish fires.
However, all of these fire extinguishing systems require high pressure storage in addition to large volume, so there is a risk of physical explosion during storage. A document “Security Analysis of Gas Fire Extinguishing System” (Fire Protection Science and Technology 2002 21 (5)) gives analysis of risks existing in the gas fire extinguishing system and lists security accidents triggered by the use of the stored pressure gas extinguishing system.
Data shows that foreign research institutions have conducted much research to look for fire extinguishing substances. The next generation of fire extinguishing technology project team (NGP) of the Building and Fire Research Centre of National Institute of Standards and Technology of America has done much experimental research work in finding novel fire extinguishing substances in replacement for halon. In the study, they found that ferrocene was a fire extinguishing substance with very strong fire extinguishing capability. Ferrocene was heated with high temperature nitrogen, carbon dioxide, or CF3H as a carrier gas and was sublimated to gas. Fire extinguishing test was carried out by applying the carrier gas together with the ferrocene vapor on a flame. It was found that addition of ferrocene can significantly reduce the extinguishing concentration of the carrier gas, thus proving that ferrocene has a very strong flame suppressing capability (Halon Options Technical Working Conference 2-4 May 2000, Flame Inhibition by ferrocene, alone and with CO2 and CF3H; Proceedings of the Combustion Institute, Volume 28, 2000/pp 965-2972, Flame inhibition by ferrocene and blends of inert and catalytic agents; Flame inhibition by ferrocene, Carbon Dioxide, and Trifluotomethane Blends Synergistic and Antagonistic Effects).
Henan Polytechnic University has also conducted research on ferrocene flame suppression and published relevant articles, such as Study of Characteristics of Heat Release Rate of Pool Fire under Action of Ferrocene, Journal of Henan Polytechnic University, 2008, Vol. 27, No. 6, Study of Characteristics of the Extinguishment of Alcohol Fire, Journal of China University of Mining Technology; 2008, Vol. 37, No. 2, Analysis of Effectiveness of Gas-phase Ferrocene in Suppressing Pool Fire, Journal of Safety and Environment, 2008, Vol. 8, No. 2, Experimental Research of Gas-phase Ferrocene in Suppressing Alcohol Pool Fire, Thermal Science and Technology, 2007, Vol. 6, No. 3, Development of a Ferrocene Fire extinguishing Experimental Platform and Experimental Study on Fire extinguishing Effectiveness, Fire Science, 2007, Vol. 16, No. 2. Further, a patent CN101327364A discloses a ferrocene fire extinguishing experiment system.
However, these studies on the extinguishing performance of ferrocene were only built on the basis of laboratory research but not put into practical application. Though a patent CN 1238226A discloses a novel aerosol fire extinguishing agent in which ferrocene is employed in the formulation of the aerosol fire extinguishing agent, ferrocene is used as a catalyst, and its flame-inhibition property is not used.
Existing aerosol fire extinguishing agents mainly include S-type and K-type fire extinguishing agents. In view of a comprehensive analysis of their performance characteristics, aerosol fire extinguishing agents mainly have the following shortcomings: owing to the occurrence of redox reaction of the fire extinguishing agent, a large quantity of gas and active particles are generated, and thereby aerosol fire extinguishing agents achieve the purpose of fire extinguishing by means of the combination of chemical and physical methods through the chain scission reaction of the active particles and coverage and suffocation by the large quantity of gas. The aerosol fire extinguishing agent undergoes combustion reaction and releases a large quantity of heat whiling releasing aerosol. Thus, it is necessary to add a cooling system to effectively decrease the temperature of the device and the aerosol and to avoid secondary fires. As a result, the device structure is complex and bulky, and the process is complicated and has a high cost. Moreover, lots of active particles lose activity due to the presence of the cooling system, resulting in greatly reduced extinguishing performance.